Self-destruct fuze

ABSTRACT

A self-destruct fuze for exploding dud projectiles that fail to function upon impact with a ground target. The fuze utilizes three separate locking devices which are each responsive to acceleration environments that a projectile experiences in a normal launch in order to keep the fuze in a safe unarmed position. A spin rotor and dashpot delay assembly cooperates to hold the fuze in an unarmed state in the event that the projectile has not seen the minimum normal spin environment. If the projectile has experienced a normal firing, but has failed to explode on impact with the target, the present invention will cause the dud to explode.

United States Patent [191 Mellen et al.

[4 1 Jan. 22, 1974 SELF-DESTRUCT FUZE [75] Inventors: George P. Mellen, Wayzata; William A. Schuster, Hopatcong, both of NJ.

[22] Filed: Nov. 27, 1972 [21] Appl. No.: 309,864

[52] lU.S.-Cl 102/71, 102/75, 102/80, 102/83 [51] Int. Cl. F42c 9/04 [58] Field of Search 102/70, 71, 75, 79, 80, 83

[56] References Cited UNITED STATES PATENTS 2,850,979 9/l958 Hardwick et a1. l02/7l 2,943,573 7/1960 Graser 102/78 X 3,465,676 9/1969 Simmen 102/80 Primary ExaminerSamuel W. Engle Attorney, Agent, or Firm-Edward J. Kelly; Herbert Berl; A. Victor Erkkila [5 7] ABSTRACT A self-destruct fuze for exploding dud projectiles that fail to function upon impact with a ground target. The fuze utilizes three separate locking devices which are each responsive to acceleration environments that a projectile experiences in a normal launch in order to keep the fuze in a safe unarmed position. A spin rotor and dashpot delay assembly cooperates to hold the fuze in an unarmed state in the event that the projectile has not seen the minimum normal spin environment. If the projectile has experienced a normal firing, but has failed to explode on impact with the target, the present invention will cause the dud to explode.

5 Claims,'17 Drawing Figures PATENTEB AN 22 IBM 3 786, 7 59 5 sum 3 BF 3 SELF-DESTRUC'II FUZE GOVERNMENTAL INTEREST The invention described herein may be manufactured, used and licensed by or for the Government for governmental purposes without the payment to us of any royalty thereon.

BACKGROUND OF THE INVENTION Various means have been used in prior art to fuze projectiles so that after launch the projectile will become armed and will explode on impact with a target. One of the problems with prior art projectiles has been with the disposal of the dud which failed to explode on impact. Firstly it is important to rid an impact area of remaining duds in order to prevent enemy personnel from reworking the duds and converting the projectiles into another munition to be used against friendly troops. Secondly it is important to avoid the existence of dud shells in areas which are later to be used by friendly troops in order to avoid these unexploded shells from inadvertently exploding, thereby injuring friendly personnel and denying the area to these troops for their strategic use. Prior art devices have used self destruct means on small caliber shells, however their time delay mechanisms have been too short for use in larger shells fired from rifled guns. In addition, these prior art devices have not been able to reliably conform to modern safety requirements for large caliber shells.

SUMMARY OF THE INVENTION The present device relates to a self-destruct fuze which causes a projectile to explode a fixed time after it has been launched and failed to explode on impact. The present invention frees the projectile from being solely dependent on a properly functioning impact sensing means. The present invention is designed to maintain a detonator in a safe out-of-line position until such time as the projectile has cleared all launch personnel and has received the necessary amount of linear and angular acceleration. This self-destruct fuze will not become activated until such time as the shell, to which it has been operatively attached, has firstly seen the proper launch environment, secondly stopped spinning, and thirdly a fixed amount of time has elapsed after the first and second aforementioned conditions.

One of the objects of this invention is to provide a self-destruct fuze for artillery projectiles fired from a rifled gun.

Another object of this invention is to provide a selfdestruct fuze for an artillery projectile which will not arm the projectile until it has seen a proper launch environment.

A further object of this invention is to provide a selfdestruct fuze for use in an artillery projectile which is capable of reducing the existence of active field duds.

Another object of this invention is to provide a selfdestruct fuze for use in an artillery fired projectile which will function in the event that the projectile has failed to explode on impact after a given time delay.

For a better understanding of the present invention, together with other and furthter objects thereof, reference is made to the following description taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a partial cut-away, top plan view of the selfdestruct fuze in a safe position showing an upper body section which holds thereon a cover, and encloses therein a dashpot assembly, a booster charge, a firing pin, and a rotor assembly.

FIG. 2 shows the fuze in the safe position with the upepr body section removed so that a top view of the lower body section can be seen showing how the spring biased rotor, spin rotor assembly, firing pin assembly and the biased centrifugal weight are structurally related.

FIG. 3 is a partial cutaway isometric view of the fuze as illustrated in FIG. 2, showing additional details of the spin rotor assembly, the rotor, and the booster charge.

FIG. 4 is a partial cutaway isometric view of the fuze as illustrated in FIG. 2, showing the position of the firing pin in relation to the detonator when the rotor is in a safe position.

FIG. 5 is a partial cutaway isometric view of the fuze illustrated in FIG. 2 showing how the setback pin and spring assembly hold the rotor so that the detonator is out-of-line with the fuze lead when the fuze is in the safe" position.

FIG. 6 is a partial cutaway isometric view of the fuze illustrated in FIG. 1 showing the position of the arming slider, the actuating device for the dashpot assembly in relation to the delay mechanism, and the position of the slider pin which acts as a connecting link between the rotor and the arming slider when the fuze is in a safe position.

FIG. 7 is a partial cutaway, top plan view of the selfdestruct fuze in an armed position showing how the rotor has been released by the centrifugal weight as a result of the spin forces of the projectile thereby permitting the rotor and the detonator carried therewith to move in a clockwise direction.

FIG. 8 shows the fuze in an armed position with the upper body section removed so that a top view of the lower body section can be seen in relation to the rotor, how the rotor has now biased the firing pin, and how the spin rotor has prevented the rotor from making further clockwise rotation.

FIG. is a partial cutaway isometric view of the rotor and spin rotor as illustrated in FIG. 8 showing additional details of the spin rotor and the rotor when the fuze is in the armed position.

FIG. 10 is a partial cutaway isometric view of the armed fuze illustrated in FIG. 8 showing how the centrifugal weight has unlocked the rotor, and how the latter has rotated about the booster charge to bias the firing pin.

FIG. I1 is an additional partial cutaway view of the fuze in the armed state illustrated in FIG. 8 showing how the setback pin and setback spring have retracted due to the force of setback and released the rotor so that it can rotate in a clockwise direction relative to the lower body section.

FIG. 12 is a partial cutaway isometric view of the fuze in the armed position illustrated in FIG. 7 showing how the arming slider pin has disengaged itself from the rotor slot.

FIG. 13 is a partial cutaway, top plan view of the selfdestruct fuze in the fired position showing how the rotorhas oriented the detonator in-line with the booster charge lead and the spring biased firing pin.

FIG. 14 shows the fuze in a fired position with the upper body and cover removed so that a top view of the lower body section can be seen in relation to the rotor. This view shows how the spin rotor has released the rotor so that it can rotate additionally in a clockwise direction, to position the detonator directly in line with the firing pin and how the detonator is initiated when the latter is suddenly released by the rotor and forcibly strikes the detonator.

FIG. 15 is a partial cutaway isometric view, as illustrated in FIG. 14, of the rotor and the spin rotor, after the rotor has been released by the spin rotor because of the termination of projectile spin.

FIG. 16 is a partial cutaway isometric view as illustrated in FIG. 14 showing the firing pin stabbing the detonator that has been rotated by the rotor.

FIG. 17 is a partial cutaway isometric view of the fired position showing the rotor in its most clockwise position relative to the arming slider.

Throughout the following description like reference numerals are used to denote like parts of the drawing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIGS. 1-6 the fuze 10 has a circular disc shaped upper body section 12 and a matching circular disc shaped lower body section 14. A cover 16 is fixedly attached to the top surface of the upper body section 12 by three fastening pins 18. The fastening pins also hold the lower body section 14 securely fastened to the upper body section 12. The lower body 14 has an integral central hollow shaft 20, which protrudes through upper axial shaft cavity body 13 and contains therein a booster charge 22. The booster charge 22 is the final explosive element in the fuze which is used to detonate a main charge (not shown). A rotor body section 24 having a central cavity 23 therein is axially and rotatably positioned by the lower body shaft and is contained within an upper body section rotor circular cavity 25 intermediate the cover 16, the upper body section 12 and the lower body section 14. The upper body section 12 has a lead cavity 26 proximately positioned adjacent said booster charge 22 and holds therein a lead charge 28 which propagates an explosion initiated from a detonator 30, located in rotor detonator cavity 31, to the booster charge 22 when the detonator 30 is moved into the fired position by rotor 24. A firing pin 32 positioned on the free end of a firing pin cantilevered spring 34, is biased by the movement of the rotor and suddenly released thereby to forcibly strike the detonator 30 when the fuze is fired.

In the safe position, as illustrated in FIGS. l-6, the detonator 30, contained in rotor section 24, is held approximately l20 out-of-line with lead charge 28. The

, rotor section 24 is maintained in this safe" position by three locks. The first locking device consists of a setback pin 36 that is biased by setback pin spring 38. The setback pin 36 in the safe position engages the setback pin rotor hole 40 and prevents the rotation of the rotor section 24 until the setback pin 36 is withdrawn by the projectiles setback force. The second locking device consists of a hinged spring biased centrifugal weight 42 whose hooked nose portion 44 engages a similarly shaped front angular rotor projection 46. The centrifugal weight 42 is held in the position shown in FIGS. 1, 2, 4 and 5 by a weight spring 48 as long as the projectile spin has not come up to its normal fired rate. A third locking device for the safe position consists of a rotor pin 50 which projects downwardly and hits the side of a non-symmetrically shaped spin rotor section 52. The spin rotor 52 and the rotor pin 50 prevent the rotor section 24 from rotating in a clockwise direction until the shell has seen a minimum amount of spin. In addition the slider pin 54 of the arming slider 56 projects from the underside of arming slider 56 through the upper body section 12 and interferes with a radial rotor notch 58. The arming slider 56 is the actuating device for the dashpot delay mechanism 60. The aforementioned motion responsive locks hold the rotor sec tion 24 in the safe position against the clockwise rotating force caused by the compression of the helically coiled rotor spring 62 which has one end 66 abutting rotor spring anchor pin 64 and its other end 68 adjacent annular rotor groove end 70. The spin rotor coiled spring 72 biases the spin rotor 52 to obstruct the rotor section 24 when the fuze is in the .safe position. The spin rotor 52 is axially positioned upon spin shaft 74 which is in turn operatively held by the lower body section 14. I

Referring now to FIGS. 7-12 the fuze is shown after being subjected to the minimum amount of linear and angular acceleration. In order to bring the mechanism into the armed condition the three aforementioned mechanical locks must be activated simultaneously by the forces of setback and spin after which the rotor section 24 is driven by the rotor spring 62 which is positioned in the annular rotor spring groove 76 and pushes against rotor spring anchor pin 64 projecting from the lower body section 14. The turning rotor section 24 pushes arming slider 56 into the dashpot assembly 60. The viscous fluid 78 in the dashpot assembly retards the motion of the rotor section 24 and thus provides an arming delay. The firing pin 32 and the firing pin cantilever spring 34 are deflected by the rotor 24 during this motion. The arming is complete when the rotor section 24 disengages itself from the arming slider 56 and slider pin 54 and is stopped by the spin rotor 52. The eccentrically shaped spin rotor 52 is caused to rotate about spin rotor shaft 74 because of its non-symmetrical shape in response to the forces exerted by the projectile spin. This centrifugal force causes the spin rotor 52 to overcome the counter torquing force of the spin rotor spring 72. The centrifugal force of spin also causes the hinged spring biased weight lock 42 to overcome the counter restraining force of the weight spring 48. The retraction of the setback pin 36 by the setback force in combination with the hinged movement of the spring biased weight permits the rotor to advance to the armed position. It should be noted that in the armed position the detonator 30 is still out-of-line with the lead charge 28.

Referring now to FIGS. 13-17 the fuze is shown in the fired position at a time when the projectile spin has decayed to a level that the restoring torque of the spin rotor spring 72 is greater than the centrifugal force exerted by spin rotor 52. The spin rotor 52 will pivot to the position shown in FIG. 15 thereby allowing the rotor section 24 to clear the spin rotor 52 and to rotate 'under the torquing force of rotor spring 62. As the the firing pin 32. The rotor section 24 in this position releases the deflected firing pin 32 which strikes the detonator 30 which in turn initiates the lead charge 28 which in turn initiates the booster charge 22 thereby causing the projectile to explode in the event that the impact fuze has failed to function.

In operation the self-destruct fuze is activated by setback forces followed by spin forces. Upon setback and spin the following events must occur for the fuze to function:

a. Setback pin 36 is driven toward the lower body section 14.

b. Spin rotor 52 is driven counter clockwise by setback and held in this position by spin.

c. Upon sufficient spin the spring biased weight 42, which has been restrained by the weight spring 48, is rotated in a counter clockwise direction.

The combined movement of the setback pin 36, spring biased weight 42, and the spin rotor 52 releases the rotor section 24. The rotor section 24, which is driven clockwise by the rotor spring 62, pushes against the slider pin 54 which in turn pushes against the arming slider 56. The arming slider 56 which works against the dashpot delay assembly 60 is retarded in its move ment and thus provides a time delay in the movement of the rotor section 24. In addition to the delay provided by the dashpot delay assembly 60, the spin rotor 52 being rotated in its most counter-clockwise position, prevents the rotor section 24 from rotating to the point of firing pin 32 release.

After a time delay the slider pin 54 is disengaged from the rotor 24 permitting the rotor section 24 to rotate in a clockwise direction. As the rotor section 24 moves, that portion of it under the firing pin 32 also moves clearing the firing pin 32 and releasing it. As soon as the firing pin 32 is released it is depressed toward the lower body section 114 by a second protrusion of the rotor section 24 which contains the detonator 30. When the rotor moves to its extreme clockwise position it releases firing pin 32 which then forcibly impacts the detonator 30 which is now in-line with the firing pin 32 and the lead charge 23. The lead charge after being activated initiates the booster charge 22 which in turn causes the dud to explode.

In the event that the fuze fails to see the normal projectile spin for a minimum time, the rotor pin 50 will engage the spin rotor 52 and prevent the fuze from functioning.

The foregoing disclosure and drawings are merely illustrative of the principles of this invention and are not to be interpreted in a limiting sense. We wish it to be understood that we do not desire to be limited to the exact details of construction shown and described for obvious modifications will occur to a person skilled in the art.

Having thus fully described the invention, what is claimed as new and desired to be secured by Letters Patent of the United States is:

I. A self-destruct fuze for causing a projectile dud to explode a fixed time after impact on a target which comprises:

a housing means having an upper body section, a

lower body section, and a cover fixedly attached rotor means biasedly positioned within said housing intermediate said upper body and lower body sections;

dashpot means operatively positioned in said housing upper body section having a slider pin protruding through said upper body section operatively engaging said rotor and preventing the rotation of said rotor means until a fixed time after said projectile is launched;

a booster charge axially positioned in said lower body section;

a lead charge radially positioned in said upper body section adjacent said booster charge;

a detonator fixedly held in said rotor in an out-of-line with said lead charge when said rotor is in a safe" and an armed" position, said rotor positioning said detonator in an in-line position with said lead charge when said fuze is in a. fired position;

centrifugal weight locking means hingedly attached to said lower body section for biasedly holding said rotor unmovable until said fuze has seen minimum spin;

spin rotor means operatively held adjacent said rotor for preventing release of said rotor until said projectile has first seen minimum spin and then has ceased spinning;

setback locking means operatively positioned in said lower body section for holding said rotor in a safe position, until said projectile is launched, and for releasing said rotor when said projectile has been properly launched; and

a firing pin means fixedly attached to said lower body section for functioning said detonator after said projectile has failed to explode on impact.

2. A self destruct fuze as recited in claim 1 wherein said upper body section comprises:

a circular disc shaped section having a centrally positioned upper body axial shaft cavity therein through which said lower body section partially protrudes, an upper body rotor cavity for permitting the rotation of said rotor within said housing, and a lead cavity proximately disposed intermediate said shaft cavity and said rotor cavity.

3. A self destruct fuze as recited in claim 2 wherein said rotor means comprises:

a rotor body section having a central cavity therein which slidably fits within said upper body rotor cavity, a setback rotor pin hole which slidably engages said setback locking means, a rotor detonator cavity circumferentially positioned in said rotor for fixedly holding said detonator therein, and an annular rotor spring groove;

a rotor spring anchor pin slidably positioned in said rotor spring groove and fixedly held in said lower body section; and

a helically coiled rotor spring compressively biased in said rotor spring groove having one end adjacent said anchor pin and the other end adjacent the end of said rotor spring groove thereby giving said rotor body section a biased torquing force.

4. A self-destruct fuze as recited in claim 3 wherein said spin rotor means comprises:

a non-symmetrically shaped spin rotor section;

a spin rotor pin axially connected to said spin rotor section, said spin rotor pin operatively held by said lower body section; and

connected to said pointedly shaped pin, said cantilever spring operatively positioned intermediate said lower body section and said upper body section and biasedly held by said rotor body section when said fuze is in the armed position, and released by said rotor when said fuze is in its fired position so that said pointedly shaped pin forcibly strikes said detonator. 

1. A self-destruct fuze for causing a projectile dud to explode a fixed time after impact on a target which comprises: a housing means having an upper body section, a lower body section, and a cover fixedly attached thereto for covering said upper body section and holding said upper and lower body sections affixed to each other; rotor means biasedly positioned within said housing intermediate said upper body and lower body sections; dashpot means operatively positioned in said housing upper body section having a slider pin protruding through said upper body section operatively engaging said rotor and preventing the rotation of said rotor means until a fixed time after said projectile is launched; a booster charge axially positioned in said lower body section; a lead charge radially positioned in said upper body section adjacent said booster charge; a detonator fixedly held in said rotor in an out-of-line with said lead charge when said rotor is in a ''''safe'''' and an ''''armed'''' position, said rotor positioning said detonator in an in-line position with said lead charge when said fuze is in a ''''fired'''' position; centrifugal weight locking means hingedly attached to said lower body section for biasedly holding said rotor unmovable until said fuze has seen minimum spin; spin rotor means operatively held adjacent said rotor for preventing release of said rotor until said projectile has first seen minimum spin and then has ceased spinning; setback locking means operatively positioned in said lower body section for holding said rotor in a ''''safe'''' position, until said projectile is launched, and for releasing said rotor when said projectile has been properly launched; and a firing pin means fixedly attached to said lower body section for functioning said detonator after said projectile has failed to explode on impact.
 2. A self destruct fuze as recited in claim 1 wherein said upper body section comprises: a circular disc shaped section having a centrally positioned upper body axial shaft cavity therein through which said lower body section partially protrudes, an upper body rotor cavity for permitting the rotation of said rotor within said housing, and a lead cavity proxiMately disposed intermediate said shaft cavity and said rotor cavity.
 3. A self destruct fuze as recited in claim 2 wherein said rotor means comprises: a rotor body section having a central cavity therein which slidably fits within said upper body rotor cavity, a setback rotor pin hole which slidably engages said setback locking means, a rotor detonator cavity circumferentially positioned in said rotor for fixedly holding said detonator therein, and an annular rotor spring groove; a rotor spring anchor pin slidably positioned in said rotor spring groove and fixedly held in said lower body section; and a helically coiled rotor spring compressively biased in said rotor spring groove having one end adjacent said anchor pin and the other end adjacent the end of said rotor spring groove thereby giving said rotor body section a biased torquing force.
 4. A self-destruct fuze as recited in claim 3 wherein said spin rotor means comprises: a non-symmetrically shaped spin rotor section; a spin rotor pin axially connected to said spin rotor section, said spin rotor pin operatively held by said lower body section; and a spin rotor coiled spring axially positioned on said spin rotor pin for biasing said spin rotor section to obstruct said rotor body section when said fuze is in the ''''safe'''' position.
 5. A self-destruct fuze as recited in claim 4 wherein said firing pin means comprises: a pointedly shaped pin; a flexibly shaped cantilever spring having one end fixed to said lower body section and its free end connected to said pointedly shaped pin, said cantilever spring operatively positioned intermediate said lower body section and said upper body section and biasedly held by said rotor body section when said fuze is in the ''''armed'''' position, and released by said rotor when said fuze is in its ''''fired'''' position so that said pointedly shaped pin forcibly strikes said detonator. 